/*
 * Title:        CloudSim Toolkit
 * Description:  CloudSim (Cloud Simulation) Toolkit for Modeling and Simulation of Clouds
 * Licence:      GPL - http://www.gnu.org/copyleft/gpl.html
 *
 * Copyright (c) 2009-2012, The University of Melbourne, Australia
 */

package cloudsim.power;

import cloudsim.Host;
import cloudsim.Log;
import cloudsim.Vm;
import cloudsim.util.MathUtil;

import java.util.List;

/**
 * A VM allocation policy that uses Inter Quartile Range (IQR)  to compute
 * a dynamic threshold in order to detect host over utilization.
 * <p>
 * <br/>If you are using any algorithms, policies or workload included in the power package please cite
 * the following paper:<br/>
 * <p>
 * <ul>
 * <li><a href="http://dx.doi.org/10.1002/cpe.1867">Anton Beloglazov, and Rajkumar Buyya, "Optimal Online Deterministic Algorithms and Adaptive
 * Heuristics for Energy and Performance Efficient Dynamic Consolidation of Virtual Machines in
 * Cloud Data Centers", Concurrency and Computation: Practice and Experience (CCPE), Volume 24,
 * Issue 13, Pages: 1397-1420, John Wiley & Sons, Ltd, New York, USA, 2012</a>
 * </ul>
 *
 * @author Anton Beloglazov
 * @since CloudSim Toolkit 3.0
 */
public class PowerVmAllocationPolicyMigrationInterQuartileRange extends
        PowerVmAllocationPolicyMigrationAbstract {

    /**
     * The safety parameter in percentage (at scale from 0 to 1).
     * It is a tuning parameter used by the allocation policy to
     * estimate host utilization (load). The host overload detection is based
     * on this estimation.
     * This parameter is used to tune the estimation
     * to up or down. If the parameter is set as 1.2, for instance,
     * the estimated host utilization is increased in 20%, giving
     * the host a safety margin of 20% to grow its usage in order to try
     * avoiding SLA violations. As this parameter decreases, more
     * aggressive will be the consolidation (packing) of VMs inside a host,
     * what may lead to optimization of resource usage, but rising of SLA
     * violations. Thus, the parameter has to be set in order to balance
     * such factors.
     */
    private double safetyParameter = 0;

    /**
     * The fallback VM allocation policy to be used when
     * the IQR over utilization host detection doesn't have
     * data to be computed.
     */
    private PowerVmAllocationPolicyMigrationAbstract fallbackVmAllocationPolicy;

    /**
     * Instantiates a new PowerVmAllocationPolicyMigrationInterQuartileRange.
     *
     * @param hostList             the host list
     * @param vmSelectionPolicy    the vm selection policy
     * @param safetyParameter      the safety parameter
     * @param utilizationThreshold the utilization threshold
     */
    public PowerVmAllocationPolicyMigrationInterQuartileRange(
            List<? extends Host> hostList,
            PowerVmSelectionPolicy vmSelectionPolicy,
            double safetyParameter,
            PowerVmAllocationPolicyMigrationAbstract fallbackVmAllocationPolicy,
            double utilizationThreshold) {
        super(hostList, vmSelectionPolicy);
        setSafetyParameter(safetyParameter);
        setFallbackVmAllocationPolicy(fallbackVmAllocationPolicy);
    }

    /**
     * Instantiates a new PowerVmAllocationPolicyMigrationInterQuartileRange.
     *
     * @param hostList          the host list
     * @param vmSelectionPolicy the vm selection policy
     * @param safetyParameter   the safety parameter
     */
    public PowerVmAllocationPolicyMigrationInterQuartileRange(
            List<? extends Host> hostList,
            PowerVmSelectionPolicy vmSelectionPolicy,
            double safetyParameter,
            PowerVmAllocationPolicyMigrationAbstract fallbackVmAllocationPolicy) {
        super(hostList, vmSelectionPolicy);
        setSafetyParameter(safetyParameter);
        setFallbackVmAllocationPolicy(fallbackVmAllocationPolicy);
    }

    /**
     * Checks if the host is over utilized, based on CPU utilization.
     *
     * @param host the host
     * @return true, if the host is over utilized; false otherwise
     */
    @Override
    protected boolean isHostOverUtilized(PowerHost host) {
        PowerHostUtilizationHistory _host = (PowerHostUtilizationHistory) host;
        double upperThreshold = 0;
        try {
            upperThreshold = 1 - getSafetyParameter() * getHostUtilizationIqr(_host);
        } catch (IllegalArgumentException e) {
            return getFallbackVmAllocationPolicy().isHostOverUtilized(host);
        }
        addHistoryEntry(host, upperThreshold);
        double totalRequestedMips = 0;
        for (Vm vm : host.getVmList()) {
            totalRequestedMips += vm.getCurrentRequestedTotalMips();
        }
        double utilization = totalRequestedMips / host.getTotalMips();
        return utilization > upperThreshold;
    }

    /**
     * Gets the host CPU utilization percentage IQR.
     *
     * @param host the host
     * @return the host CPU utilization percentage IQR
     */
    protected double getHostUtilizationIqr(PowerHostUtilizationHistory host) throws IllegalArgumentException {
        double[] data = host.getUtilizationHistory();
        if (MathUtil.countNonZeroBeginning(data) >= 12) { // 12 has been suggested as a safe value
            return MathUtil.iqr(data);
        }
        throw new IllegalArgumentException();
    }

    /**
     * Sets the safety parameter.
     *
     * @param safetyParameter the new safety parameter
     */
    protected void setSafetyParameter(double safetyParameter) {
        if (safetyParameter < 0) {
            Log.printConcatLine("The safety parameter cannot be less than zero. The passed value is: ",
                    safetyParameter);
            System.exit(0);
        }
        this.safetyParameter = safetyParameter;
    }

    /**
     * Gets the safety parameter.
     *
     * @return the safety parameter
     */
    protected double getSafetyParameter() {
        return safetyParameter;
    }

    /**
     * Sets the fallback vm allocation policy.
     *
     * @param fallbackVmAllocationPolicy the new fallback vm allocation policy
     */
    public void setFallbackVmAllocationPolicy(
            PowerVmAllocationPolicyMigrationAbstract fallbackVmAllocationPolicy) {
        this.fallbackVmAllocationPolicy = fallbackVmAllocationPolicy;
    }

    /**
     * Gets the fallback vm allocation policy.
     *
     * @return the fallback vm allocation policy
     */
    public PowerVmAllocationPolicyMigrationAbstract getFallbackVmAllocationPolicy() {
        return fallbackVmAllocationPolicy;
    }

}
